Sliding keel sailboat with a hull with reduced rolling

ABSTRACT

A sliding keel sailboat of the type comprises a sailing hull, a mast and a sailing arrangement whereon aero-dynamic forces, apt to be transferred to the hull through the mast, push, the mast being integral with a pivoting structure which can swing around a pivoting axis, parallel to a longitudinal central axis of the sailboat, in a respective seat in the sailing hull, the pivoting structure being arranged so that the crew can stand on it so as to balance the forces acting on the mast.

BACKGROUND OF THE INVENTION

The present invention refers to a sliding keel sailboat with a hull withreduced rolling.

As it is known, in the field of sailboats, different problems derivingfrom the sailing conditions and driving techniques exist. The presentApplicant addressed efforts to solve at least two problems inparticular, the first connected with the efficiency of the hull immersedin the water and the second connected with the comfort of the passengersduring sailing.

In the standard sailboats, in which fittings and equipment are tightlybound to the hull, the action of the wind onto the sail surface givesrise to some forces which are transferred to the hull by a mast. Sincethe forces acting on the mast have a considerable lever arm in respectof the centre of gravity of the hull, it results a couple which tends todetermine a certain roll angle, which angle is determined by thedifferent forces at stake, weight and position of the crew aboardincluded.

The resulting attitude or roll angle in balance conditions, causes atwofold problem: from one hand, the so-called water lines of the hullare different from condition to condition, (continuously changing incompliance with the modification of the roll angle) and therefore theycould not result appropriate in the specific state of sailing; from theother hand it results a heel attitude of the hull, to the point that theedges of the hull are partially immersed in the water or, even, thecapsizing of the whole sailboat happens (which event, is not veryappreciated by the inexperienced passengers which are aboard and also bythe crew during the winter months).

But while the second problem has a minor importance—being connected witha general condition of “comfort”—the first one is of concern in all thesailboats where extra performances are required. In fact, if it ispossible to design a hull provided to keep a constant attitude, it willalso possible identify “water lines” extremely efficient without anysort of compromise, offering great advantages to the sailboatperformance.

In the field, various attempts have been made to find an arrangement forthe hull, equipment and rigging such to maintain the hull with aconstant attitude, notwithstanding wind conditions.

Solutions which fores e to clear the mast from the hull by means ofhinges or suitable kinematic chains, are among the most tested, but noone has had a convincing and satisfying practical application so far.

An example of said design, even if applied to a keel sailboat,consequently of big dimensions, is EP-A-375.637. Said document teachesto assembly a mast to a hull through a pin which allows the lateralswing of the mast. The mast crosses the hull in full and it is belowlinked to the mass of the keel, which keel also oscillates together withthe mast. It is comprehensible how much such a solution is complex, bothfrom the mechanical as well as the hydrodynamic point of view. Further,said solution has been only conceived for sailboats with big dimensions.Furthermore it is to be noted that having a deck plane completelystable, the acrobatic entertainment, often appreciated by the crewaboard, is absent.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide a slidingkeel sailboat in which the hull immersed in the water can maintain asubstantially constant attitude for any wind condition, without thedisadvantages of the above mentioned prior art occur, while keepingunchanged the entertainment conditions for the crew aboard.

Said object is achieved by a sailboat as described in the first claim.

Other inventive aspects of the present invention are described in thedependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the sailboat according to theinvention, however, will result more evident from the following detaileddescription of a preferred embodiment, given as an example asillustrated in the annexed drawings, wherein:

FIG. 1 is an elevation view, of the stern side of the sailboat accordingto the invention, the mast standing vertical;

FIG. 2 is a view similar to that of FIG. 1, the mast being inclined of acertain angle; and

FIG. 3 is a partial schematic view of another embodiment which shows indetail the operation of the pivoting system.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A sailboat, in a way “per se” known, consists of a sailing hull 1(having volume and dimensions which depend on the specific design), amast 2, a sailing surface (not shown) as w ll as various quipment, forexample trapezes 3 or safety belts (not shown).

A sliding keel D and one or more rudders T1 and T2 are provided at thebottom of the hull.

Specific areas whereon the crew can simply stand or which are apt forcarrying on manoeuvres for driving the boat, are provided on the decksurface 1 a.

According to the invention, the mast 2 is mounted integral with apivoting structure 5, which structure in turn is pivoting around alongitudinal central axis of the sailboat, which is shown as projectionin the point P (FIG. 3).

The pivoting structure 5 is housed in a corresponding seat 1 b insidethe hull. A guide and support system can be provided between the seat 1b and the structure 5, as for example, a couple of appropriate slidingrails, which confer enhanced stiffness to the system, cooperating withthe supporting brackets of the pivoting axis (P).

In this way, the pivoting structure 5 together with the mast 2, are ableto swing, about a roll axis, with respect to the hull 1.

As all the drawings show, the pivoting structure preferably has atransversal section substantially with semicircular shape.Advantageously, the bottom surface is cylindrical and closed: thisavoids, therefore, that objects or some body parts of the crew (as forexample a foot) can fall between the pivoting structure 5 and the seat 1b in the hull from the windward side, with imaginable consequences.

The longitudinal dimension of the structure 5 can be chosen on the baseof design parameters which are not relevant to the present description.

To understand the operation, it is necessary to consider that theapplication of a pressure onto the sail surface coming from the left asshown in FIG. 3, causes a rotation of the pivoting structure 5 and ofthe mast 2, which take the new position as indicated with a broken lineand with the numerical references 5′ and 2′, respectively. a balancingsystem, such as for example a mass M ( concentrated to the bottom end ofthe mast or distributed within the pivoting structure 5) or anequalizing device (as a set of springs) which operates between thestructure 5 and the hull 1, is provided so as to avoid that the systemresults unsteady (the centre of gravity of the sail arrangement and ofthe mast, lying above the point P, naturally tends to locate below pointP).

The mass M can have a lever arm, with regard to the axis P, bigger thanthe radius of the pivoting sector 5 (as FIGS. 1 and 2 show).

To define, instead, the single balance positions of the system, uponvariation of the aerodynamic pressures on the sail arrangement—namely tobalance the tendency of the mast to fall under the wind pressure, whatwould substantially cancel the pushing effect on the sailboat—it isenvisaged that the operating crew E (for example the forward man),resting on the pivoting structure 5 can move windward its own centre ofgravity such as to create a redressing momentum on the mast/pivotingstructure assembly.

Since the pivoting structure 5 cannot have an excessive transversaldimension, considering the fact that it could derive a pronouncedinterference with the hull even for small heel angles of the mast,according to a preferred embodiment of the invention two extensionplates 4, rotatably mounted in relation to the structure 5, preferablyrotating also around the point P, are provided one for each side of thesailboat. The plates 4, in their lower position are in contact with thepivoting structure 5 (FIGS. 1 and 2).

This construction enables the crew to further displace their weighttowards the outside, so that to exercise a stronger redressing momentumon the mast/pivoting structure assembly. Since the two plates are freeeach other and pivoting in respect of the structure 5, there isn't anyconstraint on their length (along the width of the hull), since they donot integrally interfere with said hull on the lee side, as FIG. 2perfectly shows.

Moreover it is to be noticed that, since on the lee side the plate isaligned with the deck surface 1 a and the hull 1 is not subject to heel(as, on the contrary, it occurs in the traditional sailboats), it isimpossible that the same plate, even if very long, falls into the water.This, evidently, represents an additional advantage, in particular forthe eventual passengers which rest above it. Then, the fact, that thewindward plate is displaced integrally with the pivoting structure,maintains the entertainment in the trapeze man activity which, beingoutwardly displaced on the windward side, will be raised of aconsiderable height over the water surface in condition of strong wind.

Finally, retaining shrouds 6 of the mast, which link an upper portion ofthe mast with the pivoting structure 5, so as to create a wind bracingwhich makes the same mast less flexible, may be provided. Equally, aforestay and aftstay are provided, which stays, not being subject tosignificant extensions or shortenings upon variations of the roll angleof the mast, may be fixed to the longitudinal extremities of the sailinghull.

From the above stated, it is evident that the crew and the principalequipments of the sailboat exclusively make reference to the pivotingstructure, avoiding that couples or overturning forces operate on thelower sailing hull.

In other words, only forces longitudinally directed are transferred tothe sailing hull.

Therefore, the latter, in all wind conditions, stays immersed in thewater substantially with the same attitude or, at least, with a minimumroll angle: the objects expressed above are hence perfectly achieved.

According to a preferred embodiment of the invention, the balancingsystem also comprises a shock absorber device apt to slacken suddenadjustments of the mast, with regard to the hull, which are caused by aninconstant wind force (for example as a gusts).

Finally, a further embodiment of the invention provides that thepivoting structure is constrained in rotation not, or not only, around apin in the point P, but even through constraints and guide means (suchas for example, sliding rails having a track lying as a circle arch)which are located in the seat 1 b.

Anyway, it is understood that the invention is not limited to theparticular above described configurations, which only represent some notrestrictive examples of the scope of the invention, but differentvariations are also possible, all within the reach of a skilled personwithout departing from the scope of the same invention.

For example, the shape of the hull and of its water lines can be widelyaltered with regard to the above described, but still using the teachingof the invention.

And also, it is not absolutely necessary that the lower surface of thepivoting structure, for preventing a foot of the crew being trapped intothe seat of the sailing hull, on the windward side, is completelyclosed, but the same surface could have lightening holes or a meshbarrier.

1. Sliding keel sailboat of the type comprising a sailing hull, a mastand a sail arrangement, said mast being mounted integral with a pivotingstructure by a pivoting axis, parallel to a longitudinal central axis ofthe sailboat, to the hull structure, wherein said pivoting structure,free to rotate relative to the sailing hull, is arranged so as to allowthe crew to lean it to balance wind forces acting on the leeward tiltingmast, wherein at least two extension plates are further provided, onefor each sailboat edge, also said plates swinging, free of each other,about a longitudinal axis with respect to said pivoting structure, thelower position of said plates being determined, alternatively, by thecontact with said pivoting structure or with the deck surface of thesailing hull.
 2. Sliding keel sailboat as in claim 1, wherein saidpivoting structure (5) or said mast (2) have a stabilization system. 3.Sliding keel sailboat as in claim 2, wherein said stabilization systemcomprise a mass (M) having the center of gravity placed under saidpivoting axis.
 4. Sliding keel sailboat as in claim 2, wherein saidstabilization system comprise further a shock absorber device, operatingbetween the sailing hull (1) and said pivoting structure (5).
 5. Slidingkeel sailboat as in claim 1, wherein said pivoting structure (5), has asection shape as a circular sector.
 6. Sliding keel sailboat as in claim5, wherein the lower peripheral surface of said pivoting structure (5)is a portion a cylindrical surface.
 7. Sliding keel sailboat as in claim5, wherein constraint and guide means are provided between said pivotingstructure and the relative seat in the sailing hull.
 8. Sliding keelsailboat as in claim 7, wherein said constraint and guide means arerails running over an arch of a circle.
 9. Sliding keel sailboat as inclaim 1, wherein an anti-intrusion protection device is provided betweensaid pivoting structure and said seat in the sailing hull.
 10. A slidingkeel sailboat comprising: a sailing hull; a pivoting structure pivotalwithin a seat in said hull about a first axis parallel to a longitudinalcentral axis of the sailboat; a mast integrally mounted with saidpivoting structure and pivotal about said first axis; and at least twoextension plates on either side of said mast, said plates beingindependently swingable about a longitudinal axis with respect to saidpivoting structure so that a lower portion of said plates arealternatively in contact with said pivoting structure and with a decksurface of the sailing hull, said mast being rotatable from a firstposition substantially perpendicular to said hull to a second positionat an acute angle to said hull with respect to a leeward side of saidsailboat, said pivoting structure being structured and arranged so thatwhen said mast is in said second position, at least one crew memberapplies pressure to said pivoting structure from a windward side tobalance wind forces acting on the mast.
 11. The sliding keel sailboat asin claim 10, further comprising a stabilization system connected to atleast one of said pivoting structure and said mast.
 12. The sliding keelsailboat as in claim 11, wherein said stabilization system furthercomprises a shock absorber device between the sailing hull and saidpivoting structure.
 13. The sliding keel sailboat as in claim 10,further comprising an anti-intrusion protection device between saidpivoting structure and said seat in said sailing hull.